DNA fragments containing the information for gastric inhibitory polypeptide (GIP) secretin and glucagon, will be designed and synthesized by a combination of chemical and enzymatic procedures. The synthetic genes will be expressed in E. coli to produce these peptide hormones by the fusion of these genes to the beta-galactosidase gene. The analogues of GIP also will be produced by the same method to develop a new therapeuic agent for the treatment of diabetes and ulcers. The genes for amino acid substitutes of GIP will be utilized to obtain trustworthy calibration of the effect of base pair breaking on the Tm reduction for the studies of evolutionary process and gene organization in genome. Specific base change in known DNA sequences directed by the synthetic polydeoxyribonucleotides will be developed for the duplex DNA.